Phase modifier



July 2, 1929.

H. BENIOFF PHASE MODIFIER Filed Feb. 24, 1927 3 Sheets-Sheet l July 2, 1929. BENIQFF 1,719.356

PHASE MODIFIER Filed Feb. 24, 1927 s sheets-s eet 2 L c IMP f I I MPH Samm July 2, 1929. H, Blimp-F 1,719.356

PHASE MODIFIER Filed Feb. 24, 1927 3 Sheets-Sheet 3 umrEo STATES PATENT emu-1.

Patented July 2, 1929.

HUGO IBENIOIT, 0F PASADENA, CALIFORNIA, ASSIGNOB TO CARNEGIE INSTITUTION OF WASHINGTON, OF WASHINGTON, DISTRICT OF COLUMBIA, A CORPORATION OF ,THE UNITED STATES.

PHASE MODIFIED.

Application fled February'M, 1927'. Serial No. 170,715.

This invention relates to methods of and apparatus formodifying the phase of an alternating. current and particularly to the production of multi-phase currents from a source of single phase current. v I When an alternating current flows through a circuit including resistance and reactance, the current is of constant phase but the voltages across the resistance and reactance are not in phase. Although this phenomenon is well known, no simple and efficient method of obtaining split phases or multiple phases thereby'has been previously devised since an attempt to withdraw power through a circuit shunted across a part of the basic circuit results in a change in the previously observed phase displacement. In accordance with the present'invention, a load circuit may be supplied with current of a predetermined phase displacement through a.v relay of the voltage .operated type, i. e. a vacuum tube. B a proper arrangement of the tube circuit, t 1e operation of the relay is independent of the current flowing in the basic circuit; the phase of the v voltage in the load circuit being dependent solely upon the voltage across those points in the basic circuit to which the input terminals of the tube are connected.

An object of the invention is to provide a method of and apparatus for obtaining from a source of single phase current other currents whose phase relationship. is independent of the load in the circuit or circuits which they traverse. Another object relates to obtaining from a given single phase source, electric power with an electromotive force leading or lagging that of the given source by a predeterminedangle. More specifically an object is to provide a method of and apparatus for obtaining from a source of low power, single phase current, two-phase currents of materially higher power.

These and other objects of the invention will be apparent from the following specification when taken with the accompanying drawings, in which;

Fig. 1 is a circuit diagram of alternating current circuits in which phase displacement occurs;

Fig. 2 is a diagram of a circuit for obtaining an electromotive force having a large angle of displacement;

Fig. 3 is a diagram of a circuit for obtaining a split phase current in which the voltage of the derived current leads the voltage of the source; I

Fig. 4 is a diagram of a circuit for obtaining a derived current having a lagging voltage;

Fig.5 is a diagram of a circuit for amplifymg the voltage of the single phase source, and obtaining therefrom split phase currents, one being supplied from the amplified source and theother having a voltage leading the same by a predetermined angle;

Fig. is a diagramof a circuit for obtainmg split phase. currents having voltages which lag and lead, respectively, that of the source;

7 is a diagram of a circuit for obtaining split phase currents, one of which is supplied by the amplified source current and the other has a voltage lagging the first by a predetermined angle;

Figs. 8 and 9 are diagrams of circuits for obtaining three-phase currents connected in star and delta, respectively; and

Fig. 10 is a diagram illustrating an application of the invention in a power system.

In the circuit diagrams, the conventional symbols have been employed to designate the various types of reactances.

In Fig. 1', a source S of single phase current of votage E is shown as feeding into shunt circuit, one of which comprises a capacity C in series with a resistance R while the other comprises an inductance L and series resistance R The voltage'E across R will lead the voltage E by an angle 5,, and the voltage E across R will lag the source voltage E by an angle 41 the values of these angles being determined by the equations:

The voltages E,- and E will'thus form a twophase circuit in which the phases are displaced by the sum of the two phase angles.

either the lagging or leading voltage, the

precautions being taken, the grid circuit may be treated as though it were electrostatic;

. approac consequently power may be withdrawn fromthe plate circuit without appreciable altera tionof the predetermined phase relationship! With a suitable ar -j rangement of transformers or other output,

of the basic circuit.

devices, the voltage in the output circuit .will be in phase with the grid voltage or will make a constant angle with it. It thus becomes possible to derive polyphase power from single phase power and to obtain it in any number of phases with any predetermined phase relationship.

Since the tangent of the phase angle in a given circuit is determined by the ratio of resistance to reactance, it follows that the maximumdisplacement of this angle is 90. To approach this maximum value, however, the resistance R must approach zero and consequently the voltage of the displaced phase displaced by angles of 90 or greater, a number of simple circuits may be cascaded as shown in Fig.2. The source of single phase current/S and grid bias battery C arearranged in series in the input circuit of a vacuum tube amplifier V, which amplifier is provided with the usual filament battery A and plate battery B. The direct current plate circuit is completed through the resistance P and the tube functions in the ordinary manner to amplify the oscillatory currents impressed on the grid circuit. The phase displacement is provided by a series of cascaded circuits, each of which includes an impedance and-a resistance in series, the succeeding circuits being shunted across the resistance element of the preceding units. As illustrated, the series impedance Z and resistance R are shunted across the plate circuit, a second series impedance Z and. resistance R, are shunted across the resistance R and a third unit comprising the impedance Z and resistance R is shunted across theresistance R of the second unit. To preserve the phase rela-' tionship, the succeeding units in the cascade are of progressively higher impedance. As the voltage across succeeding resistances becomes progressively smaller, it may be necessary to insert an amplifier in the cascaded circuits to olfset the progressive drop. The amplifier takes the form of a second vacuum tube V which ma be operated from the batteries which supp y powerto the first amplifier. The resistance R constitutes the input circuit of the amplifier and a plate circuit is provided by a resistance or impedance P Additional phase-displacing units may es zero. To obtain a high voltage then be cascaded in shunt with the output circuit of the second amplifier. As illustrated,

to produce a two-phase power from a single phase source S. A resistance R, is shunted across the source and a cascaded phase changer C R C R is shunted across the reslstance R,.' The resistance R lsarranged in series with a biasing battery C to form the input circuit of a vacuum tube amplifier V The plate circuit of the amplifier includes a transformer T for separating the direct and alternating current'components of the space current and the load is connected across the secondary of the transformer. The voltage delivered tothe load will lead the voltage of the source by a predetermined angle, and

'when quarter-phase current is desired the phase changer is adjusted to provide an angular displacement of When the source S delivers sufficient power the current for one of the quarter phases may be drawn directly from the source, the magnitude of voltage being regulated by tapping the supply from a suitable point along the resistance R,. If, however, the source S is of comparatively low power, it is necessary to amplify the power before delivering it to the load circuit. This amplification may be obtained by inserting a vacuum tube amplifier V between the tap on the resistance R, and the loadcircuit. The connection from the tap on R includes a large blocking condenser C and the tube input circuit consists of resistance R and biasing battery C. The voltage impressed upon the amplifier V is in phasewith the voltage of the source S and the value of this voltage is regulated by the adjustable tap on the resistance'R The plate circuit of the tube V includes a. transformer T having a secondary across which the load is connect- 7 ed. If desired, condensers C C may be shunted across the primaries of the transformers T T respectively. When the phase changer is designed to provide an angular displacement of 90, the secondaries of the transformers deliver a quarter-phase current. The circuit as illustrated produces a quarterphase current in which the voltage of the derived phase leads the amplified voltage of the source. By substituting inductances for the capacities C C the voltage of the derived phase will lag the voltage of the source.

The circuit shown in Fig. 4 will deliver two-phase current derived from the single phase source S. The input terminals of the tube V, are connected across the resistance R of the basic series circuit C R and the input terminals of the second tube V are connected across the resistance R, of the basic series circuit R,.. A capacityC is introduced in the clrcuit LR to insulate the grid circuit of the second tube. The voltages of the two-phase circuit are both displaced from" the voltage of the source, one being a leading and the other a lagging voltage. When the constants are so chosen that the sum of the angular displacements is 90 electrical degrees voltage across resistance R by means of the cascaded units C, R, and 0, R impressed upon the grid of tube V,, and produces the current of leading voltage in the plate circuit P The .secondphase is delivered by the tube V, which is energized by the voltage across resistance'R The voltage across R is tapped from the resistance R by a tap which is adjustable to make the output voltage in plate circuit P equal to the voltage in the phase derived through the tube V A condenser C is introduced in the lead to the tube V to insulate the grid circuit. In this circuit, one phase has the voltage'of the source and the voltage of the derived phase is a leading voltage.

With thecircuit of Fig. 6, both voltages of the split phase current are displaced from that of the source S. As in the previous circuit, the voltage of S is amplified by tube V to provide a greater drop across the plate inductance P. Parallel phase changing circuits C, R, and L R are shunted across'the impedance P, through the insulating condenser C and biasing battery C. The leading voltage across R is applied to the grid of tube V and the lagging voltage across R, is applied to tube V The two load circuits are connected in parallel across their respective plate circuits P P with condensers O introduced to separate out the direct current component of the plate currents. This circuit may be designed to deliver quarter phase power by adjusting the constants of the phase changingunits to give angular displacements whose sum is 90 electrical degrees. I

Fig. 7 illustrates a further circuit for obtaining phase displacements of the order of 90 electrical degrees or greater. In this circuit the voltage of the source S is amplified by tube V and a cascaded phase changer L R,,L R is shunted across the plate resistance R. The tube V therefore delivers a lagging voltage to the secondary of the output transformer T The voltage across the secondary of the transformer T of the tube 2 is in phase-with the source since the voltage im-. pressed upon the grid is obtained by a connection to an adjustable tap on the resistance R of the amplifier. The usual blocking con denser C, is provided to insulate the grid circuit of tube .V,,.

The invention is not limited to the production of two phase power, and Figs. 8 and9 show circuits adapted to deliver three phase power. I

In the circuit of Fig. 8, a resistance R is shunted across the source S and two phase changing un1ts C R C 11 are cascaded across the reslstance. Vacuum tube V 18811- ergized by the voltage existing in resistance R, tube V is energized by the voltage across the terminal resistance R, and tube- V is energized with the voltage across the resistance R As the voltage drop across the resistances becomes progressively smaller. the connections to resistances R and R are adjustable for the purpose of equalizing the magnitudes of the voltages impressed upon the tubes. The secondaries of the output transformers T T and T deliver three phase,

star connected power to the load lines when the units C, R and C R are each designed to produce a leading angle of 60 electrical degrees. The low sides of transformers T and T, are connected to the high potential the star connection, the connections to the secondary delivery phase 3 are reversed.

- By substituting inductances for the capacities employed in the phase changers of Fig. 8, the voltages of the two .derived phases will lag the voltage of the source S. Three phase power may also be obtained by combining the source voltage withtwo' voltages which lag or lead by 120 and 240 electrical degrees, respectively.- To obtain displacements of 240 electrical degrees, however, a greater number of cascaded units will be required.

In the circuit diagram of Fig. 10, the source of power S may be an alternating current generator, a power line or the secondary winding of a transformer, and leads 1, 2 are connected at opposite sides of the source to provide a phase of the desired two-phase outand the adjustable tap P. The voltage drop across the terminal resistance R is impressed upon the grid of the vacuum tube V and the resultant alternating ,current voltage in the plate circuit operates through the transformer T to supply-the second phase of the output power circuit to the leads 3, 4:. A tuning condenser is preferably included in shunt with the primary winding of the transformer T. c

Although the filament and plate current for energizing the vacuum tube V may be supplied from batteries or other direct current source, these current supplies are preferably taken from the power sources. The primary L of a power transformer '1 is connected across the source S and current flowing therein induces current in the three secondary windings L L L I The secondary L supplies current for heating the filament of tube V, and is provided with a center tap at which the plate and grid returns are connected. The secondary L supplies current for the plate circuit through the rectifier tube R which tube is of the hot cathode type and is energized by the secondary L A filter of any suitable type, such as series inductances L, L and shunt capacities C C and Cg, is employed to eliminate the alternating current components from the rectified plate current supply.

It will be understood that any desired angular displacement of one or more phases may be obtained by an appropriate design of the basic circuits, and that the phases produced may be combined in various relationshipsby the use of transformers or other appropriate devices. While the invention has been particularly described in connection with the production of quarter phase and three phase current, it is apparent that split phases of other relationships may be roduced, and that power of more than time phases may be producedif desired. I claim:

1. Apparatus for transforming single phase electric power to multiphase power hav ing phases displaced by more than 90"electrical degrees, comprising a basic circuit across which the voltage of a single phase 7 source may be impressed, said circuit including a plurality of phase displacing units each operative to produce an angular displacement of substantially less than 90 electrical degrees, displacement circuits connected across separate pairs of points in said basic circuit at which voltages displaced by not less than- 90 electrical degrees occur, and electrostatic relays energized by the respective displace ment circuits, the output circuits being associated with each other to deliver multiphase power to a load.

2. Apparatus as set forth in claim 1, wherein each of said units comprises series reactance and resistance, and certain of said units are cascaded by connecting each unit in turn 4. Apparatus as set forth in claim 1, wherein one relay is energized by the source voltage and the input circuit of a second relay is connected across a part of the basic circuit at which the voltageis displaced from that of the source by 90 electrical degrees.

.In testimony whereof, I aflix my signature.

HUGO BENIOFF. 

